1. Field of the Invention
The present invention relates to a steering wheel the pad of which is non-rotatable, and more particularly, to a communication structure in which to utilize magnetism between a column and a pad.
2. Description of the Related Art
As for this kind of steering wheel, it is now known that a pad provided at the hub of a steering wheel may be equipped with electronic appliances such as a switch, a sounding device, a display device and so on which are closely associated with a klaxon, a constant speed traveling device, a transmitter, a radio, a head light or the like by making the most of the unrotatable pad.
Where such electronic appliances are installed, it is required to transmit and receive a signal between the pad and the column. As a transmitting-and-receiving means, there have been proposed a slip ring method and light beam-using method for providing the necessary pad to column communication.
The above-described methods are, however, attended with some problems which are described as follows:
Namely, in case of employing the slip ring method, inasmuch as the the number of transmittible and receivable signals is in proportion to the number of the slip rings, much information could not be transferred on account of constraints such as a size of the slip rings and the number thereof or the like.
Furthermore, the slip ring method creates defects wherein there is a possibility to cause a signal error which is referable to contact resistance produced when the slip ring comes into contact with a brush, this being deemed troublesome in performing multiplex transmission and receiving.
In addition, a light communication system involves such an arrangement that spokes are inevitably disposed between a transmitter and a receiver and hence it is necessary to take some measures toward this shielding member.
What is more, a distingushing circuit needs to be provided for the purpose of distingushing disturbance light such as solar light or the like from a light signal; and there are required light-shielding members for shielding light communication portions from the light, this unfavorably leading to an increase in number of components and further to intricacy in fabricating process.